1. Field of the Invention
The present invention relates to an apparatus for performing communication with another vehicle having similar positional data based on broadcast positional data. The present invention also relates to an avoidance operation when it is recognized that there is a possibility of a collision with another vehicle.
2. Description of the Related Art
Systems for collecting a variety of information using a vehicle mounted communication apparatus, systems for collecting destination information of each vehicle to be utilized in traffic control, and a variety of other systems have all been proposed.
Inter-vehicle communication has been proposed where a moving or stopping vehicle will notify another vehicle of its actions or of information obtained in communication between the vehicles.
With such inter-vehicle communication, along with useful data, unnecessary information is often transmitted and received. For example, even if information of future traveling/stopping of a vehicle which has brushed is received, it usually has no meaning. Therefore, in inter-vehicle communication, there are many requests to effectively select useful data from all received data.
Furthermore, Japanese patent laid-open publication No. Hei 7-333317 discloses an apparatus that transmits/receives position information between movable bodies and raises an alarm when both movable bodies are approaching a predetermined distance.
Moreover, there has been proposed a system for averting vehicle collision by performing communication between vehicles (inter-vehicle communication) and measuring the distance between the vehicles. The xe2x80x9cSS boomerang systemxe2x80x9d is one such system. In the xe2x80x9cSS boomerang system,xe2x80x9d an electromagnetic wave is broadcast, and a response is returned by vehicles which receive that signal. The response time is measured to calculate the distance between the vehicles to allow the possibility of collision to be reduced.
However, with inter-vehicle communication for measuring the distance between vehicles based on the response time of the transmitted electric wave, accurate motion information of another vehicle other than the distance between the vehicles is difficult to obtain.
In addition, it is not negligible that the avoidance operation carried out by the both vehicles that have possibility of a crash is not necessarily appropriate.
It is an object of the present invention to provide an inter-vehicle communication apparatus capable of receiving only necessary information in a vehicle by including positional data in a communication protocol.
It is another object of the present invention to provide a vehicular traveling control apparatus for executing control to avert a collision with another vehicle by obtaining accurate motion information of the other vehicle through inter-vehicle communication.
According to one aspect of the present invention, a communication pattern is determined based on the position of the user""s vehicle. Therefore, transmission data is received in the vehicle that has received data in accordance with the communication pattern at that position. Thus, a signal required for reception can be automatically selected.
For example present position and projected positions at two seconds later, four seconds later, . . . , n seconds later are represented in the form of time data and positional data, and the communication pattern is determined based on these data. As such a communication pattern, the PN series for the spread spectrum or the frequency hopping pattern may be adopted. For example, when the PN series is determined based on the time and position and then transmitted, the inverse spread is performed only in a vehicle using the same PN series to receive signals. In other words, on the receiving side, only signals that coincide with the future time and position of the user""s vehicle.
Further, it may be preferable to determine a search range for the communication pattern based on a range related to traveling of the user""s vehicle, whereby this vehicle can communicate with another vehicle in that range.
When it is determined that there is a possibility of collision, it may be preferable to select a communication pattern for emergency. This enables identification of the emergency communication from any other communication.
Furthermore, it may be preferable to narrow the search range when another vehicle approaches. This can narrow the search range to select only a specific emergency communication to be performed.
Moreover, according to another aspect of the present invention, existence probability data can be calculated based on the positional data of the user""s vehicle and position error data. The accuracy of this existence probability data can be greatly increased by utilizing the position error data.
Use of the existence probability data can allow precise motion information of another vehicle to be obtained to assist carrying out of accurate avoidance control.
Additionally, according to yet another aspect of the present invention, relative position data of the user""s vehicle and another vehicle obtained from the inter-vehicle communication is used to generate the existence probability data of the user""s vehicle in order to execute avoidance control.
In addition, according to a further aspect of the present invention, the user""s vehicle and another vehicle do not perform the uniform avoidance operation even when there is a possibility of a collision. Rather, the operation for averting collision is executed based on the priority of the user""s vehicle and of the other vehicle. This can prevent affecting the travel of the other vehicle or the traffic flow while still effectively avoiding collision.
Furthermore, when the user""s vehicle travels on a privileged road, it is preferable to suppress the avoidance operation of that vehicle and give priority of the avoidance operation to another vehicle. This enables avoidance of a collision without adversely affecting any other vehicle running on the privileged road.
Moreover, in regard to priority, the difficulty of the avoidance operation and the influence on other traffic also depends on the speeds at which the vehicles are travelling. For example, when the speed of the user""s vehicle is lower than that of another vehicle, it is relatively easy to execute an avoidance operation through the user""s vehicle. Accordingly, determining the priority based on the vehicle speed can effectively avoid collision.
In addition, avoiding collision with a first vehicle is pointless if this action increase the possibility of a collision with a second vehicle. Taking into account the possibility of collision with the second vehicle when the user""s vehicle is performing an avoidance operation, it is preferable to carry out the avoidance operation when there is no possibility of collision with an additional vehicle. This can avoid collisions and help maintain smooth traffic flow.
Additionally, in the inter-vehicle communication, transmission/reception information for determining which vehicle should move to avert a collision can assist in effectively avoiding collision.
Further, even if the user""s vehicle takes priority, it is preferable to determine that avoidance operation should not be carried out upon receiving data representative of execution of the avoidance operation from another vehicle. For example, the user""s vehicle executes the avoidance operation in principle, even when it takes priority, unless data indicating that another vehicle is performing an avoidance operation is received from that vehicle.